Draw bench loading measurements



Jan. 29, 1963 R. M. MANNING ETAL ,0

DRAW BENCH LOADING MEASUREMENTS Filed Nov. 50, 1959 2 sheets -sheet 1 2523 i3 7 4 24 2 2 VARIABLE-SPEED ll 2 I9 1 REVERSIBLE I 0.0 MOTOR 2 I8 20ii [4 l2 6 33 [Q I v I 5 0c. INPUT 3 4 35 40 I8 32 A v RECTIFIER 5Q 30 38 52 A x x 40 Y Y 2 2 FIG I f V C! o 0.

(I L|J+ o T I? i g .IIXX w ,0 9.1 W (I 0 SPEED O)F DRAW F|G.2 62 M WINVENTORS RALPH M. MANNING BYWILLIAM J..SCHULTZ THElR ATTORNEY V Jan.29, 1963 R. M. MANNING ETAL 3,075,636

DRAW BENCH LOADING MEASUREMENTS Filed Nov. 30, 1959 2 Sheets-Sheet 2 3OTACHOMETER GENERATOR SERVO MECHANISM INVENTORS RALPH M. MANNING BYWILLIAM J. SCHULTZ "MFFMLW THEIR ATTORNEY 3,h75,636 DRAW BENCH L UADENGMEAfiUEEMENTS Ralph M. Manning, Winchester, and William .li. Schultz,

Lynnfield, Mass, assignors to General Electric Company, a cerporation ofNew Yorlr Filed Nov. 30, 1959, Ser. No. 856,112 12 Claims. (Ci. Edd-3)This invention relates to draw benches of the type used to draw metaltubing or bars down to desired crosssectional dimensions, and moreparticularly, to an arrangernent for indicating and recording deviationsfrom the maximum allowable loading or stress which may be exerted on thedraw bench as a result of the drawing operation, and to a method forutilizing such deviations in the operation of a draw bench.

I has been found that mechanical overloading of draw benches can occurwithout electrical overloading of the draw bench electric drive motor.The loading and stresses exerted on a draw bench during a drawingoperation varies both with the speed of the draw and the instantaneouspower provided by the drive motor. In the absence of means toinstantaneously coordinate the two variables, control of the draw benchin the past has been largely a matter of operator experience andjudgment.

However, draw benches are frequently large and expensive pieces ofequipment. For example, the draw bench to which the subject inventionhas been successfully applied utilized a 250 horsepower direct currentmotor with draw bench speeds of 80 feet per minute to 240 feet perminute. In one plant it was found that mechanical overloading of drawbenches was found to cause frequent damage to the gearing and breakageof draw chains, and in one case a bench was actually pulled oif thefactory floor causing many thousands of dollars of damage to the bench,plus the loss of production during equipment downtime.

It is an object of this invention to provide an arrangement toinstantaneously indicate mechanical overloads of a draw bench over avariable speed range.

it is a further object of this invention to provide an improved methodof indicating and recording the times at which a draw bench isoverloaded during operation.

it is yet another object of this invention to indicate and utilizedeviations from the maximum allowable mechanical loading of a drawbench.

Other objects and advantages of the invention will be come apparent asthe following description proceeds and the features of novelty whichcharacterize the invention will be pointed out with particularity in theclaims an nexed to and forming a part of this specification.

In accordance with one form of the invention, means are provided toproduce an electrical signal which is proportional to the power appliedto the draw bench, means are provided to produce an electrical signalproportional to the speed of movement of the draw bench, and means areprovided for combining the electrical signals and indicating mechanicalloading placed on the draw bench relative to the maximum allowableloading.

More particularly, an electrical signal is developed proportional to theelectrical input of the motor driving the draw bench, and a tachometergenerator is utilized to provide an electrical signal which isproportional to the speed of the draw bench. The two signals provideelectric currents which are proportioned by adjusting means such thattheir eifects upon the indicating instrument are made equal and oppositefor combinations of speed of the draw bench and the instantaneous powerof the drive motor which result from a given loading on the draw bench.If the given loading is the maximum allowable, the electric instrumentwill indicate deviations of draw bench loading below or above themaximum allowable. In the preferred embodiment, the electric instrumentis incorporated as part of a recorder to maintain a record of the benchloading.

For a better understanding of this invention, reference may be had tothe following description taken in connection with the accompanyingdrawings in which:

FIG. 1 is a schematic representation of a draw bench incorporating theinvention;

FIG. 2 is a plot of the instantaneous draw bench drive motor powerversus the speed of the draw illustrating the linear relationship ofconstant load curves which result;

FIG. 3 is a preferred embodiment of an instrument which combines theelectrical signals representing the variables of FIG. 2 to provide asingle indication of the deviation of the loading applied to the drawbench from the maximum allowable loading;

FIG. 4 illustrates relationships between the variables of FIG. 2 whichare desirable in the instrument of FIG. 3;

FIG. 5 is an alternate embodiment of the instrument shown in FIG. 3;

FIG. 6 is an enlarged View of the die shown in FIG. 1; and

FIG. 7 is an alternate embodiment of the invention.

Referring to FIG. 1, a draw bench is illustrated schematicallycomprising a movable chassis or driven member I mounted on wheels 2 forlinear movement along rails 3 and 4 an fastened to the draw chain 5through connecting member 6.

The draw chain 5 moves between sprocket wheels 7 and 3 which along withrails 3 and i are securely fastened to the factory floor. One of thesprocket wheels 7 is rotatably driven by a direct current or DC. drivemotor 18 through intermediate reduction gearing such as gears 11 and i2and their associated shafts l3 and 1 respectively. Different speedranges may be provided through use of change gears in the gearing. Thespeed and direction of travel of the chassis l for a given ratio ofgears 11 and 12 are determined by the speed and direction of rotation ofthe motor iii. A direct current motor is utilized since the direction ofrotation may be readily controlled through the polarity of the appliedvoltage and the speed of rotation may be varied through control of themagnitude of the field current.

The pipe, tubing, or bar 18 which is being drawn or reduced in crosssection is drawn through die 19 to provide a bar of reduced diameter18'. Die 19, as best shown in FIG. 6, is attached to the factory floorby support 2% and contains a tapered opening 21 through which the barpasses. The bar 18 is drawn through the opening 21 of the die byclamping one end 23 of the pipe to the clamp member 24 carried by achassis 1 and moving the chassis away from the die in the directionindicated by the arrows of FIG. 1. In operation a continuous drawingprocess is accomplished by moving chassis 1 through control of motor 10to the region of die 19, clamping the pipe 18' to clamp member 24 andpropelling the chassis 1 along the rails 3 and d in the direction of thearrows until the stop or end of the rails 25 is reached. The clampmember 24 is then loosened, the chassis l is returned to the region ofthe die and the process repeated.

In order to appreciate the magnitude of the stresses involved in thedrawing operation, it may be noted that a draw bench to which thesubject invention has been applied provides pulls of up to 50,000 lbs.with a linear speed of draw or movement of chassis 1 being feet perminute to 240 feet per minute through field current control of a 250horsepower motor.

To obtain maximum bench output the bench speed should be as rapid aspossible, limited however by the aoreese loading capabilities of thedraw bench. Draw speeds will therefore vary for different types ofmetals or metals havinng a variable range of alloys in accordance withmanufacturing tolerances. Also, through use of a plurality of dies, aplurality of pipes are often drawn at the same time by a single bench.The mechanical stresses or loading imposed upon the draw bench are afunction of both the speed of the draw and the power input to the drawbench delivered by the motor Jill. In practice, a draw bench operatorhas been guided by indications of draw bench speed or power input.However, because of the relatively fast and variable speeds of the draw,it has been found difficult and impractical for the operator to note andcorrelate one or more readings in order to determine if the maximumallowable loading of the draw bench were being exceeded. Also, it hasbeen found that draw benches are often overloaded by an operatorattempting to obtain maximum bench output.

In accordance with the present invention, electrical signals aredeveloped which represent the speed of movement of the chassis 1 and theinstantaneous power of the motor 10. The two signals are combined in aninstrument to visually and/ or audibly indicate mechanical overloadingof the draw bench.

An electrical signal proportional to the speed of the draw is obtainedby coupling the rotor of a tachometer generator 30 to the shaft 31 ofsprocket wheel 8. The tachometer generator provides the electricalsignal indicated as YY in FIG. 1 which is proportional to the speed ofrotation of shaft 31 which is in turn proportional to the speed oftravel of the chassis 1.

An electrical signal representing the instantaneous power of the motoris obtained through use of a direct current transformer 32 associatedwith the D.C. power input lines 33 and 34. In order to provide a pureDC. signal which may be readily combined with the D.C. voltage outputprovided by the tachometer generator 39, the output of the D.C.transformer 32 is fed throuugh rectifier 35 to provide an output XXwhich is proportional to the power of the motor 18. The voltages XX andYY provide currents I and l respectively, when applied in circuit withan indicating instrument.

It has been found that if the signal I representing the drive motorinput power, is plotted against the signal I representing the speed ofthe draw, a linear plot results for constant mechanical stress on thedraw bench as shown in FIG. 2.

This relationship is utilized in an instrument 40 for combining thecurrent I and l A preferred embodiment of such an instrument isindicated schemactially in FIG. 3.

Referring to FIG. 3, the voltage XX is fed to a pair of series connectedstator windings 41 and 42 while the voltage YY is fed to a pair ofseries connected stator windings 43 and 4-4. A pair of rotor windings 45and 4-6 are wound upon rotor 39 which carries pointer 47 to cooperatewith scale 48 to indicate the angular deflection of the rotor windings.Spring 38 biases rotor 3? to a central position relative to scale 48.The rotor windings 45 and 46 are electrically connected in series andenergized by a D.C. voltage provided by rectifier 48'. The rectifier 48is energized by an alternating current source 50 and the output thereofis controllable by current limiting resistor as. The stator windings 41and 42 and the polarity of the applied voltage XX is selected such thatthe rotational torque provided by the interaction of the magnetic fluxesprovided by current flow through windings 41, 42 and 45 is opposite tothe rotational torque provided by the interaction of the magnetic fluxesbetween windings 43, 44 and 46. The angular deflection of the rotorwindings 45 and 46 and therefore of the pointer 47 is determined by thedifference in the torques provided by the current I and that provided bythe current I FIG. 4 illustrates the desired relationship between therotational torques provided in response to the currents I and I Thetorque versus current characteristic produced by the voltage YY may beadjusted by rheostat 52 connected in series with the tachometergenerator 34) as shown in FIG. 1. t is desirable to adjust the twotorque characteristics, so that they are mirror images of each other tomake it possible to calibrate the instrument 49 to show the approximateamount of deviation from the maximum mechanical loading curve. Thetorque characteristics are made to be equal and opposite for allconditions of draw bench power and draw bench speed which combine toprovide the maximum allowable draw bench mechanical loading, or someother given loading related thereto. Hence, an instrument such as a Zerocenter deflection instrument may be utilized to indicate the maximumallowable or safe mechanical load on the draw bench at the centerposition with deflections from the center position indicating loadswhich are below or above the maximum allowable.

The instrument as may then be used as an indication of how muchadditional stress can safely be put on the draw bench at any given time.The instrument 49 may conveniently comprise the deflection mechanism ofa strip chart recorder to provide a record of the mechanical stresswhichhas been applied to the draw bench during operation in addition toinstantaneous loading indications. The strip chart recorder is indicatedschematically as 43' in FIG. 1 with reference line 50 indicating themaximum safe mechanical loading of the draw bench. Contacts associatedwith the recorder can be utilized to energize an audible alarm when themaximum allowable loading is exceeded.

When the torque characteristic curves of FIG. 4 have been adjusted asdescribed above, a given change in either the current input of the motorIt or the speed of the carriage 1 of the draw bench will represent adefinite change in the stress applied to the draw bench. An increase inthe current input of motor 10 will produce an increase in instrumenttorque resulting from the increase of current I which tends to drive theinstrument upscale while an increase in the speed of travel of thecarriage 1 will provide an increase in current l which produces anincreased torque which tends to drive the instrument downscale. Any timethat the two torques are in balance, the draw bench will be operating atmaximum capacity without overloading. If the speed of travel of thecarriage 1 should increase without an increase of current being suppliedto the motor 1f}, the instrument 40' will deflect downscale against thebias of spring 38 indicating that the mechanical load on the draw benchhas been reduced. Conversely, if the speed of travel of thechassislshould decrease without a decrease in the current supplied tothe motor 10, the instrument 40 will deflect upscale indicating anincrease in load on the draw bench.

FIG. 5 illustrates an alternate embodiment of the instrument 49.Referring to FIG. 5, it will be seen that the stators 55 and 56 comprisepermanent magnets. The rotor windings 57 and 58 are wound upon armature54. The voltages YY and XX are connected to the moving coil windings 57and 58 and the poles of stators 55 and 56 are arranged such that thetorques developed between the interaction of the permanent magnetstators and the magnetic field provided by current flow through thewindings 58 and 57, respectively, tend to produce deflections inopposite directions in a manner similar to that described in connectionwith FIG. 3. The pointer 59 is attached to the armature 54 around whichthe rotor windings 57 and 58 are wound and cooperates with scale 60 toindicate the mechanical loading of the draw bench relative to themaximum allowable loading 62. Spring 61 establishes the center positionof pointer 59 in the absence of a net deflection torque.

While the subject arrangement has been shown in corn bination withdirect current circuits, the invention can readily be applied toalternating current circuits.

FIG. 7 illustrates an alternate embodiment of the invention whichenables the direct calibration of the indicator in the magnitude of theloading imposed upon the draw bench rather than an indication of theapproximate magnitude of deviation item a predetermined or maximumallowable loading. To enable a direct calibration of the instrument itthe product of the electrical signals In and IYY should be realized.

Referring to FIG. 7, it will be seen that the output YY of tachometergenerator 3% is used to control the positioning of the wiper 65 ofpotentiometer 66 through the servo mechanism 57 which rotates the wiperan amount proportional to the voltage YY. A battery 68 is connectedacross the potentiometer 66 and the voltage YY provided between one endof the potentiometer 66 and the position of arm 65 relative to one endthereof is proportional to The voltage YY is used to energize the rotor69 of the instrument Iii while the series connected stator windings 71and 72 of the instrument are energized by the voltage XX. The deflectionof pointer '73 in response to the combined torque of I I I and I isindicated on scale 74 which may be directly calibrated in pounds loadingof the draw bench.

However, it has been found that the arrangement shown in FIG. 7 is moreexpensive and complex than that of the previously described embodimentsof the invention which indicate loading deviations above and below themaximum. Such indications have been found to be satisfactory, eventhough the relative magnitudes thereof are only approximate and may varyunder certain conditions, since the maximum allowable loading isadjusted to be accurate over the range of operating conditions.

Therefore, while particular embodiments of the subject invention havebeen shown and described herein, they are in the nature of descriptionrather than limitation, and it will occur to those skilled in the artthat various changes, modifications, and combinations may be made withinthe province of the appended claims without departing either in spiritor scope from this invention in its broader aspects.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

1. An instrument for indicating the mechanical loading of a draw benchof the type in which a driven member draws material through a diecomprising: means to provide a first signal proportional to the speed ofthe driven member of the draw bench, means to provide a second signalproportional to the instantaneous power of the means which drive saiddriven member, means to combine said first and second signals, means toindicate the resultant of said combined signals, and means to adjust therelative efiects of said first and second signals upon said indicatingmeans to provide the same indication for combinations of speed of thedriven member and power of the drive means which result from a givenloading on said draw bench, said given loading being related to themaximum allowable loading of said draw bench.

2. An instrument for indicating the mechanical loading of a draw benchof the type in which a member draws material through a die comprising:means to provide a first electrical signal proportional to the speed ofthe driven member of the draw bench, means to provide a secondelectrical signal proportional to the instantaneous power of the meanswhich drive said driven member, means to combine said first and secondelectrical signals 6 and to indicate the resultant of said combination,and means to adjust the relative effects of said first and secondelectrical signals upon said indicating means to provide the sameindication for combinations of speed of the driven member and power ofthe drive means which result from a given loading on said draw bench,said given loading being related to the maximum allowable loading ofsaid draw bench.

3. An instrument for indicating the mechanical loading of a draw benchof the type in which a member driven by an electric motor draws materialthrough a die comprising: means to provide a first electrical signalproportional to the speed of the driven member of the draw bench, meansto provide a second electrical signal proportional to the electricalinput of the motor which drives said driven member, means to combinesaid first and second electrical signals and to indicate the resultantof said combination, and means to adjust the relative eiiects of saidfirst and second electrical signals upon said indicating means toprovide the same indication for combinations of speed of the drivenmember and power of the drive means which result from a given loading onsaid draw bench, said given loading being related to the maximumallowable loading of said draw bench.

4. An instrument for indicating the mechanical loading of a draw benchof the type in which a driven member draws material through a diecomprising: means to provide a first signal proportional to the speed ofthe driven member of the draw bench, means to provide a secondelectrical signal proportional to the instantaneous power of the meanswhich drive said driven member, means to combine said first and secondsignals, and to indicate the resultant of said combination, and means toadjust the relative effects of said first and second signals upon saidindicating means to provide effects which are equal and opposite forcombinations of speed of the driven member and power of the drive meanswhich result from a given loading on said draw bench, said adjustmentproviding an indication of a loading which is releated to the maximumallowable loading of said draw bench.

5. An instrument for indicating the mechanical loading of a draw benchof the type in which a member driven by an electric motor draws materialthrough a die comprising: a tachometer generator to provide a firstelectrical signal proportional to the speed of the driven member of thedraw bench, means to provide a second electrical signal proportional tothe electrical input of the motor which drives said driven member, meansto produce and combine torques which are proportional to said first andsecond electrical signals and to indicate the difference therebetween,and means to adjust the relative effects of said first and secondelectrical signals upon said indicating means to provide torques whichare equal and opposite for combinations of speed of the driven memberand power of the drive means which result from a given loading on saiddraw bench, said given loading being related to the maximum allowableloading of said draw bench, said indicating means indicating draw benchloadings above and below said maximum allowable loading.

6. An instrument for indicating the mechanical loading of a draw benchof the type in which a driven member of the draw bench draws materialthrough a die comprising: means to provide a first signal proportionalto the speed of the driven member of the draw bench, means to provide asecond signal proportional to the instantaneous power of the means whichdrive said driven member, means to provide a third signal which is thereciprocal of one of said first mentioned signals, means to combine saidthird signal and the other of said first mentioned signals and toindicate the product thereof, said indicating means being calibrated toprovide indications of the mechanical loading of said draw bench.

7. A method of providing material of a desired cross section comprising:passing a portion of material of a cross section greater than thatdesired through a fixed die a 7 of the desired cross section, securing amovable member to the said portion, driving the said movable member awayfrom said die by driving means, deriving a first signal representing thespeed of said movable member relative to said fixed die, deriving asecond signal representing the power input to said driving means,combining the efiects of said first and second signal and indicating theresultant thereof, and controlling the speed of said movable member inaccordance with the indication of the combined efiects of said signals.

8. A method of drawing a material to a desired cross section through afixed die without exceeding the maximum allowable loading of the drawbench comprising: securing a movable member to the material being drawn,drawing the movable member away from the fixed die by a driven member,deriving a first electrical signal proportional to the speed of saiddriven member, deriving a second electrical signal proportional to theinstantaneous power of the means which drive said drive member,combining said first and second signals and indicating the resultantthereof, adjusting the relative effects of the first and second signalsto provide the same indication for combinations of speed of the drivenmember and power of the drive means which result from a given loading onthe draw bench and which is related to the maximum allowable loading onthe draw bench, and controlling the speed of said driven member inaccordance with said indications.

9. A method of drawing a material to a desired cross section through afixed die without exceeding the maximum allowable loading of the drawbench comprising: securing a movable member to the material being drawn,drawing the movable member away from the fixed die by a member driven byan electric motor, deriving a first electrical signal proportional tothe speed of said driven member, deriving a second electrical signalproportional to the electrical input of the motor which drives saiddriven member, combining said first and second signals and indicatingthe resultant thereof, adjusting the relative effects of the first andsecond signals to provide a predetermined indication for combinations ofspeed of the driven member and power of the drive means which resultfrom a given loading on the draw bench and which is related to themaximum allowable loading on the draw bench, and controlling the speedof said driven member in accordance with said indications.

10. A method of drawing a material to a desired cross ection through afixed die without exceeding the maximum allowable loading of the drawbench comprising: securing a movable member to the material being drawn,drawing the movable member away from the fixed die by a driven member,deriving a first electrical signal proportional to the speed of saiddriven member, deriving a sec- 3 end electrical signal proportional tothe instantaneous power of the means which drive said driven member,combining said first and second signals and indicating the resultantthereof, adjusting the relative effects of the first and second signalsupon the indicator to provide effects which are equal and opposite forcombinations of speed of the driven member and power of the drive meanswhich result from a given loading on the draw bench and which arerelated to the maximum allowable loading on the draw bench, andcontrolling the speed of said driven member in accordance with saidindications.

11. A method of drawing a material to a desired cross section through afixed die without exceeding the maximum allowable loading of the drawbench comprising: securing a movable member to the material being drawn,drawing the movable member away from the die by a member driven by anelectric motor, deriving a first electrical signal by a tachometergenerator proportional to the speed of said driven member, deriving asecond electrical signal proportional to the electrical input of themotor which drives said driven member, providing and cornbinin torqueswhich are proportional to said first and second signals and indicatingthe difierence therebetween, adjusting the relative effects of the firstand second signals upon said indicating mean to provide torques whichare equal and opposite for combinations of speed of the driven memberand power of the drive means which result from a given loading on thedraw bench to indicate draw bench loading above and below the maximumallowable loading, and controlling the speed of said driven member inaccordance with said indications.

12. A method of drawing a material to a desired cross section through afixed die without exceeding the maximum allowable loading of the drawbench comprising: securing a movable member to the material being drawn,drawing the movable member away from the fixed die by a driven member,deriving a first electrical signal proportional to the speed of saiddriven member, deriving a second electrical signai proportional to theinstantaneous power of the means which drive said member, deriving athird signal which is the reciprocal of one of said firstmentionedsignals, combining said third signal with the other of saidfirst-mentioned signals and indicating the product thereof, andcontrolling the speed of said driven member in accordance with saidindications.

References Cited in the file of this patent UNITED STATES PATENTS2,452,244 Knudsen Get. 26, 1948 2,602,538 Bimba et al. July 8, 19522,640,352 Ellison et al. June 2, 1953 2,886,170 Kerr May 12, 1959

1. AN INSTRUMENT FOR INDICATING THE MECHANICAL LOADING OF A DRAW BENCHOF THE TYPE IN WHICH A DRIVEN MEMBER DRAWS MATERIAL THROUGH A DIECOMPRISING: MEANS TO PROVIDE A FIRST SIGNAL PROPORTIONAL TO THE SPEED OFTHE DRIVEN MEMBER OF THE DRAW BENCH, MEANS TO PROVIDE A SECOND SIGNALPROPORTIONAL TO THE INSTANTANEOUS POWER OF THE MEANS WHICH DRIVE SAIDDRIVEN MEMBER, MEANS TO COMBINE SAID FIRST AND SECOND SIGNALS, MEANS TOINDICATE THE RESULTANT OF SAID COMBINED SIGNALS, AND MEANS TO ADJUST THERELATIVE EFFECTS OF SAID FIRST AND SECOND SIGNALS UPON SAID INDICATINGMEANS TO PROVIDE THE SAME INDICATION FOR COMBINATIONS OF SPEED OF THEDRIVEN MEMBER AND POWER OF THE DRIVE MEANS WHICH RESULT FROM A GIVENLOADING ON